SUMMARY Our interdisciplinary group proposes to continue our theoretical and experimental studies of the NMR behavior of lung in pulmonary edema. Previous data from our group and from other investigators have shown that NMR techniques can not only quantify lung water, but can also contribute substantially to the characterization of pulmonary edema and other types of lung injury. In view of these data, the proposed studies will be focused on the characterization of pulmonary edema and other experimental models of lung injury (bleomycin-, and endotoxin-induced injury). We propose to characterized lung injury using three approaches (each corresponding to one of the three specific aims of the present proposal): 1) Determination of the effects of the internal magnetic field inhomogeneity by our symmetric/asymmetric imaging technique. These studies include the comparison of theoretical production obtained from models developed to simulate pulmonary edema in its different stages (intestinal and alveolar ) and to quantify alveolar, flooding with NMR, gravimetric and morphometric data from normal and injured lungs (excised lungs and anesthetized living animals). 2) Determination of NMR relaxation times T1 and T2. We propose to study the mechanisms of spin- lattice and spin-spin relaxation in lung and to apply T1, Hahn T2 and CPMG T2 measurements to the characterization of lung injury in excised lungs and in vivo. 3) Determination of lung water self-diffusion. We propose to study the role of factors possibly affecting water diffusion in lung tissue as well as i colleagues and elastin at various levels of molecular and intermolecular organization, the feasibility of in-vivo characterization of pulmonary edema by water diffusion imaging. We expect that the proposed studies will improve our understanding of the mechanisms determining the NMR behavior of normal and injured lungs and our ability to characterize pulmonary edema and other types of lung injury using NMR techniques. We also anticipate that the results of the proposed studies will provide a basis for the utilization of NMR methods not only for basic studies of experimental lung injury, but also for the clinical evaluation of pulmonary disease.